Apologies for my absence. As a partial atonement I'll give you a word which, although tremendously important, has not made it into any dictionary I know of, either printed or on-line.

The new technology of horizontal fraccing has made it economically feasible to drill into vast shale deposits in many states, even famously difficult ones like Michigan and New York.
– Reason Magazine (on line), May 13, 2009

fraccing (short for "fracture stimulation") – a technique to improve production flow in an oil or gas well: pushing in a sand/water mix under high pressure, in order to spread and hold open cracks across the formation
(verb: to frac)

This definition is adapted from Alberta Oil magazine, April 2009, which says, "[F]raccing has evolved into a high industrial art … This breaks up a lot of rock, making a lot more gas available. These new technologies are enabling us to access a whole lot more low-permeability [poorly flowing] rock than you would ever be able to reach with a vertical well.”

Tempus fugit – time flies (or more accurately, "time flees") From Latin fugere "to flee" we get fugitive, subterfuge and centrifuge (centrifugal force: "fleeing the center"), and also today's word.

fugacious – apt to flee away or flit. Hence fleeting, of short duration, evanescent (of things); or fleeing, ready to run away (esp. of persons)

Both senses deserve illustration, and the "fleeing" sense ties into a yesterday's quote.

Yesterday we saw the problem of underground oil that flows too sluggishly. But conversely, the fact that it can flow raises another problem. Who owns a mineral under a piece of land, if the mineral can't be trusted to stay there until the landowner mines it? if it can "flee"?

Unlike solid minerals, such as coal and iron, oil and gas are fugacious. ... By the late 1920s, petroleum's growing economic importance was stymied by the legal question of ownership. … A landowner held absolute title to the subsurface petroleum if the courts applied the traditional common law. But petroleum's fugacious nature prohibited one landowner from exercising his absolute right to extract his petroleum without infringing on a neighbor's respective right.
– Nicholas George Malavis, Bless the pure & humble: Texas lawyers and oil regulation, 1919-1936‎

Oil and gas in place are minerals, but because of their fugacious qualities, they are incapable of an ownership distinct from the soil.
– Illinois Supreme Court, 1939 (taken from secondary source)

And the sense of fugacious as "fleeting", transitory (rather than "fleeing"):

… the rain conspires with the wind to strip the fugacious glory of the cherry blossoms …
– Malaysia Star, ‎May 3, 2009‎

In the 1940's, with domestic help scarce and fugacious, eating out has gained a new popularity …
– Robert Sharon Allen, Our Fair City‎

To the extent that a legislative majority acts thus as a permanent bloc, not a fugacious vote-trading coalition, it resembles a political party.
– James M. Buchanan, in Competition and cooperation: conversations with Nobelists about economics (Alt, Levi, and Ostrom, editors)

This message has been edited. Last edited by: wordcrafter,

"Fugue" in simple form can be either the contrapuntal musical form or the psychological state.

And, of course, there is "fug-ue". Lexicographers differ on its exact meaning.

Yesterday we mentioned centrifuges …

In monitoring Iran's nuclear program, one key indicator is whether it possesses a certain difficult-to-produce steel alloy which is exceptionally hard and strong. This special alloy is a key component of the latest generation of super-powerful centrifuges used to enrich uranium.

Iran's efforts to produce highly enriched uranium are in chaos and the country is still years from mastering the required technology. Iran is also believed to be critically short of key materials for producing a centrifuge production line to highly enrich uranium - in particular the so-called maraging steel, able to be used at high temperatures and under high stress without deforming
– The Guardian, January 28, 2007

Manhattan District Attorney Robert M. Morgenthau announced today a 118-count indictment of a Chinese citizen and his company for charges relating to the proliferation of illicit missile and nuclear technology to the Government of Iran. The company is a major supplier of banned weapons material to the Iranian military. [T]he materials shipped included: … 24,500 kilograms of maraging steel rods.
– District Attorney's news release, April 7, 2009 (some ellipses omitted)

maraging – a process for strengthening steel by slow cooling and subsequent age hardening; the resulting steel is called maraging steel
[etymology: the cooling converts the carbon-in-iron solution to a form called martensite. The word maraging means martensite + aging.]

dacoit – a member of a band of armed robbers, in India or Myanmar
[from Hindi for "robbery by a gang"]

. . .It is easy to remember my conversation with Phoolan Devi, the Bandit Queen. [S]he was rarely short of an entertaining response.
. . .How come an illiterate, low caste, diminutive woman had managed to lead a gang of fearsome dacoits in the Chambal Valley? India had a long history of warrior queens, she replied. "Why don't you ask those Congresswallahs why they made Indira Gandhi prime minister?"
. . .I told her that she would go down well in London. She seemed intrigued and said she didn't have a passport. Could I help her get one?
. . .I tried to remind myself that I was talking to a woman who was supposed to have killed 22 high-caste Thakurs in revenge for the gang rape she had suffered.
– The Telegraph, July 2001 (ellipses omitted). The full article is worth a read.

penetralia – the innermost parts; the "innards"
[emphasizes "private" or "secret". Often used of a building: the holiest parts of a temple; the private family-chambers of a palace.]

… the spring … should be hallowed for the use of the vestal virgins, who were to wash and cleanse the penetralia of their sanctuary with those holy waters.
– Plutarch's Lives (John Dryden translation)

With his screwdriver, blunt and long, … he cracked the shields hiding the machine's penetralia. A screw popped and flew into the shadows.
– Daniyal Mueenuddin, In Other Rooms, Other Wonders

quote:

With his screwdriver, blunt and long, …

Seems like penetralia should have something to do with gentalia.

Thoughts On the Word of the Day

For some time I’ve used my genitalia
To plug up female penetralia
And those ladies -- they love it
Since I sure can shove it
And, machine-like, perform without falia.

quote:

Originally posted by tinman: Seems like penetralia should have something to do with gentalia.

Originally posted by wordcrafter: … vestal virgins … the penetralia of their sanctuary

In hindsight, I should have saved "penetralia" for a theme of "Words that Sound Dirty". For shame that I didn't have a sufficiently dirty mind to think of it!

I shall endeavor to remedy that defect.

welkin – the vault of the heavens; the sky
Often used with a sense of awe (first quote), particularly of a loud, primal, and powerful sound that "makes the heavens ring" (second quote).

Then the television camera swung upward to show the welkin, the lovely dome of the Earthly sky.
– Piers Anthony, On a Pale Horse

And oh but the lads were fair taken aback;
Then sudden the order wis passed tae attack,
And up from the trenches like lions they leapt,
And on through the nicht like a torrent they swept.
On, on, wi' their bayonets thirstin' before!
On, on tae the foe wi' a rush and a roar!
And wild to the welkin their battle-cry rang,
And doon on the Boches like tigers they sprang …
– Robert W. Service, The Haggis of Private McPhee

quote:

For shame that I didn't have a sufficiently dirty mind to think of it!

Some of us excel in lewd thinking. It's a gift.

I always thought a "welkin" arose following a blow to the foreskin. And I thank god for my lewd gift.

gammadion – a certain symbol, described below.
The name arises because the symbol can be described as four copies of the Greek letter Γ (gamma): one in upright position; the others made by successively rotating the first a quarter-circle, clockwise, around its bottom-left point.

"He said it's really an ancient symbol called the gammadion because it's made up of four capital gammas joined in the middle. Gamma was the third letter of Greek alphabet. It was also called a fylfot. That's a secret emblem. The early Christians used it as a kind of disguised cross, to avoid persecution.
– Alan Robbins, A Small Box of Chaos

This symbol or its mirror image were used in many cultures, perhaps because they are is easy to draw, and naturally each culture had its own name for that symbol. English used this Greek-based name, which is of course not a familiar word.

But you know that symbol quite well by another name, a name that English took from Sanskrit. It comes from svastí "well-being, fortune, luck" [sú good + astí being], and that happy origin is very ironic, for the word now has an extreme negative connotation.

The word is swastika.